// Copyright (c) 2023 IBM Corp.
// All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package lambda

import (
	"testing"

	"github.com/stretchr/testify/assert"
)

func TestFactorial(t *testing.T) {
	fct := Y(func(r func(int) int) func(int) int {
		return func(n int) int {
			if n <= 0 {
				return 1
			}
			return n * r(n-1)
		}
	})
	assert.Equal(t, 3628800, fct(10))
}
